Answer:
x = 147
Explanation:
the sum of the interior angles of a polygon is
sum = 180° (n - 2) ← n is the number of sides
here n = 7 , then
sum = 180° × 5 = 900°
sum the interior angles and equate to 900
x + 141 + 112 + 129 + 106 + 139 + 126 = 900
x + 753 = 900 ( subtract 753 from both sides )
x = 147